bettas can live in bowls because of their labyrinth organ, id put him in
something bigger then the cup he came in. your gonna need to clean that
every day and that much cleaning is stressful. put him in atleast a half
gallon bowl or a gallon bowl. the half gallon you clean twice a week, and
the gallon u clean once a week. id also get your water tested asap.
petshops usually test for ammonia for free just ask and bring a sample of
your water in. here are some good site with treatment info about bettas.
www.bettatalk.com www.bettastarz.com